Mobile machinery such as agricultural tractors, bulldozers, track tractors, skip loaders, all-terrain vehicles and earth grading tractors, generally referred to as a “tractor,” typically are provided with a suitable power plant, a source of fluid under pressure and or a source of electric current. The fluid pressure source includes suitable valve control means. The tractors typically include an implement mounting system known as a three-point hitch. The three-point hitch includes a pair of opposed spaced apart lateral bottom-link arms located at the rear of the tractor body or frame rotatably connected to the tractor with ball joints which are affixed to the frame or body of the tractor at a selected distance of typically 12 to 30 inches above the ground and extend on each side of a center draw bar. The free distal ends of the arms typically include a ball rotatable in a socket with an axial hole extending there through.
A third arm, called a top-link arm, is also rotatably connected with a ball joint to the tractor frame at a point about 30 to 60 inches above ground and centered above the bottom-link arms. The free distal end of the top-link arm is fitted with a rotatable ball with an axial hole extending there through for connecting to a center point on an implement in alignment with studs. Free ends of the two bottom-link arms and the top-link arm provide three-points of attachment to implements and therefore is referred to as a three-point hitch. The length of top-link arm is generally adjustable by means of a built in turn-buckle assembly. This provides for manual leveling of the attached implement. The top-link arm turn buckle assembly can be replaced with a hydraulic cylinder for quick controlled manual or automated adjustments of the length of the top-link arm resulting in adjustments of the attached three-point implement.
The bottom-link arms are connected to a lift-link arm to provide a means for lifting such as a suitable power lift mechanism, for example one or more hydraulic cylinders. This provides the capability to raise and lower the two bottom-link arms and thus the implement which is connected to the three-point hitch. Because the free ends of all three arms are connected to the tractor with ball joint type connections, all three arms may freely pivot to the left and the right any time the three-point hitch has the implement raised off the ground. On older tractors, an additional bar called a stabilizer arm is provided, if desired, and is connected to one of the first two bottom-link arms and to a fixed point on the tractor. On newer tractors, two stabilizer arms are provided, one for each bottom-link arm and they are also connected to a fixed point on the tractor. The stabilizer arms allow the bottom-link arms to still be raised and lowered by hydraulic means, but the implement is held stable with reference to the horizontal plane, and cannot swing to and fro as before.
The attached implement can include a transversely extending tool bar or frame member having laterally spaced apart studs extending from the front tractor-facing side of the implement for removable attachment to the sockets held within the distal ends of the bottom-link arms. In addition to the bottom-link arm attachment hardware means is an upper attachment hardware means for the attachment of the top-link arm.
A three-point hitch is standard equipment on most agricultural and earth grading tractors. The use of a three-point hitch provides lifting, lowering and tilting mechanisms to attached agricultural implements, such as agricultural implements. The tractor three-point hitch allows the attached tool or implement to be raised and lowered, tilted horizontally and tilted vertically, all such movements and adjustments provided by hydraulically activated cylinders or manual crank screw devices. Front three-point hitches, while available, are less common than rear three-point hitches on agricultural tractors.
The three-point hitch provides for a quick attachment of various implements needed on a tractor. In addition, when the implement is in the raised or lowered position, lateral movement of the three-point bottom-link arms is freely available. To limit lateral movement of the implement in the raised or lowered position, the user can add a stabilizer arm comprising a longitudinal member having a selected adjustable length attachable to a swing arm attachment point on the tractor body or frame with the opposing end attaching to the same implement stud as the adjacent swing arm to limit lateral movement of the bottom-link arms. Many tractor brands are now factory supplied with three-point hitch bottom-link stabilizer arms. Controlled lateral movement of an attached implement is not provided with a three-point hitch.
Earth-moving equipment in the construction and farming field has rapidly changed for the better in recent years with the introduction of Global Positioning Systems (GPS) and laser guidance systems. Current GPS guidance systems for earth-moving and agricultural tractors generally are designed to auto-steer the tractor. Much of the guidance involves steering the tractor in a straight line to form a straight road or straight row of crops. Since most agricultural and earth grading tractors are steered by the front end of the tractor, the rear end mounted three-point hitch attached implement may not align in a straight line with the front steered end of the tractor. This misalignment would normally occur while the tractor is turning 180 degrees around at the end of the crop row and then joining onto the next crop row in the other direction. This misalignment would also occur while the tractor is in the middle of the crop field and the tractor veered slightly off line of the crop straight line forcing the tractor operator to correct the steering of the tractor. This steering correction of the tractor can also shift the rear end of the tractor in the opposite direction of the steering correction causing the rear three-point connected implement to also veer off course of the straight crop row and possibly damage the crops while cultivating the field or misalign the crops while planting. Lasers have come into play in the earth-moving and agricultural field mostly by controlling grade leveling implements on the tractor in an up and down motion for achieving a level or sloped grade.
Conventional laterally moving implement toolbars pivot on four parallel supporting arms extending out from the front of the supporting frame. Short sized supporting arms provide limited lateral movement of the toolbar section of the implement. The short lateral movement is exacerbated by the positioning of the tool mounting bar being too close to the frame structure that mounts to the tractor three-point hitch. Mounting brackets further decrease the tool mounting bar clearance to the frame structure. Pivoting-support-arms pivot in either direction limiting the length of the lateral movement to much less than the length of the pivoting-support-arms. The weight that these pivoting-support-arms can support on the toolbar with heavy implements is dependent on the strength of the pivot arms and their pivot joints. The pivot joints need to sustain a tremendous weight load when handling a heavy implement as they pivot side to side. This weight load is compounded and increased if the pivoting-support-arms are increased in length.
Two-point hitch configurations present a different set of limitations for use of lateral connection devices. The three-point hitch invention differs from a two-point hitch in the mounting ability by utilizing the advantage of the top-link arm attachment to the tractor frame, the improved locations for the sleeves that provide the sliding housings, a more versatile and stable two tier stacked movable implement attachment section compared to the one movable toolbar and a more stable and functional two or more tiered stacked movable implement attachment section compared to the one movable implement attachment section.
Several patents teach methods of steering and controlling tractor mounted implement attachment systems to two-point and three-point hitch systems. U.S. Pat. No. 3,208,535 by Fischer teaches an automatic steering system for implements; U.S. Pat. No. 7,530,405 by Kollath et al. teaches a quick coupler mechanism, U.S. Pat. No. 4,019,753 by Kestel teaches an adjustable three-point tractor hitch; U.S. Pat. No. 4,463,811 by Winter teaches an implement with a laterally movable frame structure with limited lateral movement; and U.S. Pat. No. 5,931,234 by Trowbridge teaches a retractable three-point hitch mounted, vertically and laterally adjustable toolbar. U.S. Pat. No. 4,930,581 by Fleischer teaches a guidance control device for agricultural implements using a hydraulic cylinder to pivot the implement frame and implement to the left or to the right to correct lateral position with respect to the tractor and the previously processed rows. U.S. Pat. No. 3,208,535 by Fischer teaches an automatic steering device and a plant stem sensor.
Existing systems for pulling or pushing implements suffer from a significant disadvantage, particularly that the implement can go off course, particularly during turns. This can result in destroyed crops, inadequate application or over application of chemicals used for crops, unplowed soil, and other deleterious effects. These problems can occur even when the mobile machinery, such as a tractor, is on course.
Therefore, there is a need for a system that can allow an implement to be pushed or pulled that helps maintain the implement on track, even when the mobile machinery used for pulling or pushing the implement is off track.